Aquariums are generally equipped with an air pump which encourages the settling of microparticles, and possibly with a carbon dioxide generator which encourages the growth of plants contained in the aquarium. These bubbles are drawn in by the water pump, which circulates water through the filter, and expand in the filter. This air or this gas lowers the water level and may cause the impeller blades to come out of the water, giving rise to a cavitation phenomenon, then cause suction to stop and place the installation in a situation where prime is lost. Furthermore, in the event of a power cut or a stopping of the filter, for example while food is being distributed to the fish, the air trapped in the vessel tends to leave this vessel and tends to follow the easiest path. If air gets into the suction side, the siphoning conditions are eliminated and the filter will no longer be able to restart.
A filter external to a tank is provided which can operate without additional noise resulting from cavitation of the pump as a result of the presence of a water and air emulsion, which can restart without problems and without risk of losing its prime after a stoppage due to a power cut or to a deliberate interruption resulting, for example, from the cleaning of the filter.
To this end, the filter to which it relates, of the type comprising a vessel sealingly closed by a lid, the vessel containing at least one basket acting as a housing for filtering components and comprising a top wall bearing sealingly in the central part of the lid and allowing communication with this central part which contains a water-circulating pump, the water being conveyed through the lid by piping passing through the latter, moving down into the vessel on the outside of the basket, entering the basket via its bottom, passing upward through the basket over the filtering components and leaving the basket at the top and in the central part thereof to be sucked up by the pump and delivered to piping passing through the lid toward the pipe delivering to the tank, comprises means for automatically removing air from the water delivery side. As any air that might be contained in the filter is removed automatically from the delivery side, the suction side always has a head of pressure which means that the pump operates normally, without cavitation and without the risk of losing its prime, as soon as it is switched on.
According to one characteristic of this filter, in which the top wall of the basket comprises a collar delimiting a water outlet opening and intended to bear in a groove of the lid, sealing being afforded by a seal, the collar has at least one radial opening. This arrangement gives an air passage at the top of the filter and at a peripheral part thereof, toward the suction zone.
It has been noted that if there is air in the suction zone, particularly in the zone situated near the suction shaft, a residual pocket of air that cannot be reabsorbed is formed.
To remedy this disadvantage, in the filter according to the invention, comprising a suction intake arranged in the interior wall of the lid and comprising a cylindrical component which is mounted in a collar integral with the lid and the central part of which comprises a suction shaft, the collar has at least one through-slot arranged facing an opening in the cylindrical component when the latter is in the position mounted in the collar. Furthermore, the cylindrical component comprises an end wall connecting its peripheral part to the suction shaft, in which end wall at least one hole is made. It is thus possible, at the periphery of the suction shaft, to recover the air which lies in the upper part, and for this air to be removed parallel to the suction shaft to prevent it from building up in this zone with the ensuing disadvantages.